Most typical liquid crystal display (LCD) panels use thin film transistors (TFTs) to control deflection of liquid crystal (LC) molecules. A traditional manufacturing process for the TFT includes: sequentially forming a gate electrode, a source electrode, and a drain electrode of the TFT on a glass substrate, and connecting the source electrode and the drain electrode by an active layer which is usually made of amorphous silicon. With development in technology, researchers are beginning to use an indium gallium zinc oxide (IGZO) as a material of the active layer to replace the N+/a-Si (as shown in FIG. 1). Compared with the amorphous silicon, the IGZO has advantages of reduced TFT sizes, integration of a simple external circuit into the panel to enable a mobile device to be light and thin, and two-thirds power reduction compared to before. The IGZO further has advantages of increased pixel aperture rate of the LCD panel, improved image quality, improved electron mobility rate to 20-30 times as before, and greatly reduced response time of the LCD.
However, in actual use, characteristic and efficiency of the TFT using the IGZO are not ideal. As shown in FIG. 2, a middle current slowly increases with voltage, and a current value of more than 10*10−6 A is obtained only when the voltage exceeds 10 V. Generally, the voltage of 10 V is defined as Ion (current when connecting the TFT), and the voltage of −5 V is defined as Ioff (current when disconnecting the TFT), when Ion/Ioff is more than 10−6 A, the IGZO may be applied to the TFT device. However, in FIG. 2, because Ion/Ioff is less than 10−3 A, the characteristic efficiency of the typical IGZO TFT is not high.